This invention relates to a method for continuously producing heated and roll-shaped food from raw material and an apparatus using the same.
In a conventional method of producing a heated and roll-shaped food such as an eggroll or a flavored eggroll, a raw material (stirred egg) is first fried in a sheet form on a pan or an iron plate, and then the sheet-shaped material is laminated or rolled into a desired shape. That is, the conventional method for producing the heated and shaped food utilizes a semi-continuous cooking process.
The applicant of this invention has proposed various apparatuses to approach the conventional process to a continuous one. Particularly, the applicant's attention is given to a method of producing a roll-shaped heated food using a horizontal-type frying drum. This method using the horizontal-type frying drum has the following construction.
The frying drum is rotatably mounted on a frame such that an inclination angle in its axial direction is freely adjustable, and a heater is also disposed so as to confront a lower portion of the outer peripheral surface of the frying drum. In addition, a scraper for scraping out the heated material is freely slidably disposed along the inner peripheral surface of the frying drum, and a take-up guide roller is disposed along a slightly higher position than an sliding edge portion of the scraper with respect to the inner peripheral surface of the frying drum and in such a manner as to be rotatable in the opposite direction to a rotational direction of the frying drum. Further, an oil coating roller is disposed so as to be in contact with the inner peripheral surface of the frying drum, and a material supply device is disposed at a position where materials are supplied or poured onto an upper portion of the inner peripheral surface of the frying drum.
The applicant has conducted various experiments using the above method, and has obtained the following recognitions.
At first, when a raw material having higher fluidity is poured onto the inner peripheral surface of the frying drum, the raw material is more extensively spread out (or thinly expanded) on the inner peripheral surface of the frying drum. Therefore, the rotational speed of the frying drum can be set to a relatively high speed. Inversely, when the raw material has lower fluidity, the spreading of the material is reduced. Therefore, in this case, the rotational speed of the frying drum is reduced to assure the spreading of the material. That is, the fluidity of the raw material and the rotational speed of the frying drum are dependent on each other.
Secondarily, unlike the fluidity of the raw material and the rotational speed of the drum, a frying temperature, that is, a heating temperature of the frying drum does not directly pertain to the spreading of the raw material. That is, the spreading of the raw material is not dependent on the heating temperature. However, the following recognition is obtained in a process where in a state where the raw material is spread out and then fried, that is, gelled on the inner peripheral surface of the drum, the material is partly exfoliated and reversed by the take-up guide roller and the scraper which are provided adjacently to the inner peripheral surface of the frying drum, and then the gelled material is rolled up in a roll shape with the exfoliated and reversed part of the gelled material being a core of the roll. That is, the following facts are found out.
If the heating temperature is sufficiently high, the raw material which has swelled up on the inner peripheral surface of the frying drum due to the gelation is in a semi-fried state where no fluidity is developed, and thus the gelled material is liable to be exfoliated. Therefore, when the gelled material which has swelled up along the inner peripheral surface, that is, along an arc surface of the frying drum is upwardly moved by the rotation of the drum to the position where its weight acts on itself, the gelled material is automatically exfoliated from the inner peripheral surface of the drum and then reversed at the tip portion thereof. That is, it is found that the scraper and the take-up guide roller are not necessarily required. Inversely, if the heating temperature is low, the exfoliation and reverse of the gelled material is insufficiently performed because of the insufficient gelation, so that it frequently occurs that the material is rolled up with distortion and unevenness. In other words, it is found that a shaped food which is homogeneous and symmetric is difficult to be obtained.
As described above, the tip edge portion of the material which has been exfoliated and reversed by its weight or the scraper and the take-up guide roller is overlaid over the front surface of the material. Since the gelation of the front surface of the material is relatively delayed, that is, is more insufficient in comparison with that of the back surface of the material, the tip edge portion of the material and the front surface portion of the material over which the tip edge portion is overlaid are integrated with each other because these portions is still in a semi-fried state, and thus have fluidity. During this overlaying process of the material, the drum continues to be rotated, and thus the integrated portions serve as a next core to roll up the raw material into a roll-shaped material. Once the core is formed, the gelled raw material which is successively swelling up is found to be continuously wound around the core because its weight and an angular moment act on the core insofar as the rotation of the drum is not stopped.